The invention relates generally to Call Waiting-Call Identification on a telephone network and more particularly to providing call waiting-caller ID in a packet switched network.
Call waiting-caller ID is used to notify a user currently on a first call of a waiting second phone call to the same phone number (call waiting). A telephone may be off-hook and connected to a first phone call. When there is another incoming call to that telephone number, a central office switch sends two consecutive call waiting indication signals. If the telephone is attached to a caller ID box, that caller ID box sends back an acknowledgement signal to the central office switch after receiving the first call waiting indication signal. If the central office switch hears this acknowledge signal from the caller ID box within a certain amount of time, it will send tones to the caller ID box that represent the name and number of the second caller.
The user can then look at the second calling party name displayed on the caller ID box before deciding whether to flash hook to the second call. If the user generates a flash hook signal before the central office generates the second indication signal, the user is connected to the second party. If the user does not generate a flash hook signal before the second indicate signal, the central office terminates the second call.
The central office uses Frequency Shift Keying (FSK) signals for sending the information about the second caller to the caller ID box. To prevent the user from hearing all of these FSK signals, the caller ID box temporarily breaks the downstream voice path between the central office switch and the user""s telephone. The central office switch will not send the FSK signals unless the calling party ID box replies with an acknowledgement signal. This prevents FSK signals from reaching a telephone that does not have a caller ID box. After the FSK signals have been transmitted from the central office to the caller ID box, the voice path is reestablished.
For this call waiting-caller ID feature to work, the caller ID box must respond to the indication signal within a predetermined amount of time. This time period however is less than the round trip time currently provided by Voice Over Internet Protocol (VoIP) equipment. Specifically, VoIP equipment used in High Speed Fiber Cable (HFC) networks take too much time to forward the indication signal from the central office switch to the caller ID box and then return the acknowledge signal from the ID box back to the central office switch. This timing limitation prevents circuit switched caller ID protocols, such as GR-303, from being used in packet switched networks.
The present invention addresses this and other problems associated with the prior art.
The invention uses a novel signaling protocol for conducting call waiting-caller ID messaging. Instead of waiting for a remote acknowledge back from the caller ID box, an acknowledge signal is generated locally at the IP network gateway. This allows the packet switched network to meet the timing requirements of the circuit switched network. The gateway essentially tricks the central office switch into believing an actual acknowledge signal was sent from the caller ID box. The central office switch accordingly sends the caller ID information which is then propagated across the IP network to the caller ID box. The invention allows integration of the circuit switched network signaling standards, such as GR-303 signaling standard, into packet switched networks.